Gas Selectivity Control in Co3O4 Sensor via Concurrent Tuning of Gas Reforming and Gas Filtering using Nanoscale Hetero-Overlayer of Catalytic Oxides

Hyun Mook Jeong, Seong Yong Jeong, Jae Hyeok Kim, Bo Young Kim, Jun Sik Kim, Faissal Abdel-Hady, Abdulaziz A. Wazzan, Hamad Ali Al-Turaif, Ho Won Jang, Jong Heun Lee

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Co3O4 sensors with a nanoscale TiO2 or SnO2 catalytic overlayer were prepared by screen-printing of Co3O4 yolk-shell spheres and subsequent e-beam evaporation of TiO2 and SnO2. The Co3O4 sensors with 5 nm thick TiO2 and SnO2 overlayers showed high responses (resistance ratios) to 5 ppm xylene (14.5 and 28.8) and toluene (11.7 and 16.2) at 250 °C with negligible responses to interference gases such as ethanol, HCHO, CO, and benzene. In contrast, the pure Co3O4 sensor did not show remarkable selectivity toward any specific gas. The response and selectivity to methylbenzenes and ethanol could be systematically controlled by selecting the catalytic overlayer material, varying the overlayer thickness, and tuning the sensing temperature. The significant enhancement of the selectivity for xylene and toluene was attributed to the reforming of less reactive methylbenzenes into more reactive and smaller species and oxidative filtering of other interference gases, including ubiquitous ethanol. The concurrent control of the gas reforming and oxidative filtering processes using a nanoscale overlayer of catalytic oxides provides a new, general, and powerful tool for designing highly selective and sensitive oxide semiconductor gas sensors.

Original languageEnglish
Pages (from-to)41397-41404
Number of pages8
JournalACS Applied Materials and Interfaces
Volume9
Issue number47
DOIs
Publication statusPublished - 2017 Nov 29

Keywords

  • catalytic overlayer
  • CoO
  • gas filtering
  • gas reforming
  • gas selectivity
  • gas sensor
  • methylbenzene

ASJC Scopus subject areas

  • Materials Science(all)

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